There are numerous situations where dust or other particulate matter should be separated from a stream of flowing gas. In particular, street sweepers utilize a strong air suction to pick up dust which is drawn into a debris collection hopper within the street sweeper, with the air passing on out of the hopper, impelled by a centrifugal pump or the like.
The dust-laden air cannot be spewed into the atmosphere without thwarting the main purpose of the street sweeper. If filters are used, they become clogged very quickly because of the high quantities of dust picked up by the street sweeper. Accordingly, some street sweepers use a recirculating flow of air to keep the collected dust within the sweeper. However, the concentration of dust that flows along with the air becomes unduly high, and requires a dust trap which does not utilize a filter.
While numerous designs of dust traps are known, many of them have excessive pressure losses as an inevitable part of effective dust collection. In accordance with this invention, a dust trap which does not use a filter is provided which combines a low pressure loss with efficient separation. Also, besides having an improved combination of low pressure loss and good dust separation, the dust trap of this invention is of simple construction, and the collected dust is easily removed from it. Thus, an improvement in both efficiency of operation and cost of construction and operation is provided by the invention of this application.